100% you hit the nail on the head. The owners of PUBG (or whomever it is doing this) are complete shit heads.He did, however that was directly inspired by the Survivor GameZ mod, which Brendan Greene did NOT create. So he copied a mod for DayZ, which itself was a mod for Arma 2. I'm sure the release of The Hunger Games had absolutely nothing to do with his "inspiration" either. And of course, let's not forget every "last man standing" mode for god knows how many FPSs prior to that. In terms of game evolution, this would be like the creators of Team Fortress 2 suing Overwatch.
That's what so insane about this. It's a copycat suing another copycat. The irony aside, the fact that he made hundreds of millions of dollars apparently wasn't enough for him, making him a sore WINNER on top of it. If I was in his shoes I would think one of the following:
"Gee, well they're maintaining their game a lot better than I am, I guess that's why they're so successful."
"Gee, they made a lot of money copying someone else and tweaking it... just like me!"
"Gee, at least I'm still one of the most financially successful indie devs ever making 100s of millions of dollars from being in the right place at the right time and can do absolutely anything I want with my life."
Pick which one suits you, that's why this is a shit show any way you slice it.
Fix your game and compete.